ADOT uses new technique to ‘slide’ new I-40 Bellemont bridges into place

PHOENIX – A new technique that basically slides precast bridges into place has greatly reduced delays for the Bellemont community with an Arizona Department of Transportation project replacing spans over Interstate 40 at Transwestern Road west of Flagstaff.

Using this technique, which the contractor proposed, allowed crews to replace the bridges during a nine-day closure of Transwestern Road over I-40 rather than having the six to eight months of restrictions required for a traditional bridge replacement project.

Joining ADOT engineers in a process called value engineering, which analyzes plans looking for ways to improve quality and value while reducing time needed to complete improvements, the contractor proposed casting the new bridges whole to the east of the existing bridges and then moving them into place in a process that works much like sliding components into place. ADOT approved the plan.

Once the new bridges were complete, crews diverted I-40 traffic to the on- and off-ramps in order to demolish the old bridges. Workers then used hydraulic jacks to lift and move the new Bellemont/Transwestern Road bridges into place. That part of the process took about four-and-a-half days.

ADOT regularly looks for accelerated bridge construction methods and other innovations that can reduce delays and inconvenience for drivers. Earlier this year, for example, the agency used a process known as a geosynthetic reinforced soil-integrated bridge system to rebuild the bridges on I-40 at Meteor City Road, creating abutments by putting in alternating layers of granular fill reinforced with synthetic material. That process also cut construction time by months.